Pulmonary oxygen uptake and heart rate kinetics during the six-minute walk test in transplant recipients.

ABSTRACT

BACKGROUND: The effect of organ transplantation on arterial compliance, pulmonary oxygen uptake (VO2p) and heart rate kinetics during the 6-minute walk test (6-MWT) remains unknown. METHODS: Twenty-two thoracic (heart and/or lung) organ transplant recipients (TOTR, 51+/-12 years) and 30 abdominal (kidney, kidney-pancreas, or liver) organ transplant recipients (AOTR, 46+/-11 years) from the 2006 Canadian Transplant Games, and 37 healthy controls (HC) completed a 6-MWT. VO2p, heart rate kinetics, and arterial compliance were determined. RESULTS: The 6-MWT distance and highest VO2p were significantly lower in TOTR and AOTR versus HC. The highest 6-MWT heart rate was lower in TOTR (11%) and AOTR (13%) versus HC. VO2p kinetics were slower in TOTR (52+/-11 sec, PHeart rate kinetics were slower in TOTR (100+/-49 sec) versus AOTR (41+/-21 sec, Partery compliance were 26% (P=0.007) and 19% (P=0.004) lower, respectively, in TOTR versus HC. Large artery compliance was 14% lower in TOTR versus AOTR (P=0.017). 6-MWT distance was significantly related to VO2p kinetics (r=-0.35) and the highest 6-MWT VO2p (r=0.72).

CONCLUSIONS:

TOTR and AOTR have abnormal VO2p kinetics, which is secondary to prolonged heart rate kinetics and impaired vascular function in TOTR, but not AOTR.